This whole time I’ve been trying to figure out what caused the fog? I figure the mud was caused by rain, but not sure about the rest of the conditions. And what caused the girl that she’s looking after to be this way? Did she go insane after being in these conditions after a while? And who is Daniel? So many unanswered questions.

As a series written in the 1st person, you’ll know the reasons behind the fog and rain when he knows. As for the wife, Catherine, and their son, Daniel, a little more can be learned from the first two in the series
http://ficlets.com/stories/29596
http://ficlets.com/stories/30280